Cancer can be viewed as a curse on life of any man or woman. Although some tumors that are malignant can be curable, it comes at a cost of unbearable pain and mental trauma. X-ray based techniques are being used for many decades for detecting tumors. These techniques are applied at the expense of exposure to high ionized radiation levels. Magnetic Resonance Imaging (MRI) is another technique which is a non invasive medical diagnosis for detecting tumors. However, MRI is quite expensive test and the powerful magnetic field of the MRI system may damage an external hearing aid or cause a heart pacemaker or electrical stimulator, or neuro stimulator to malfunction. In recent times, the rapid advancement in radar and microwave technology has attracted the attention of the biomedical engineering community for application to medical imaging. The capability for penetrating waves into human body, non ionizing radiation and possibility of high resolution through UWB technology makes microwave technology an attractive alternative in biomedical imaging. In this thesis, first a comparative study of UWB antennas proposed in the open literature for imaging is performed. This study outline some of the most significant intrinsic limitations of these antennas. Next taking into account a wide range of technical and medical concerns, this thesis addresses the analysis and designing of a novel antenna for imaging tumors inside the human body in the frequency region of 3?10 GHz. Thus, we propose an effective design strategy that combines theoretical inputs, and technological constraints to design the novel leaky slot antenna. We believe that our results pave the way for future research oriented to the design of a complete microwave imaging medical system for medical application.